Patchwork [RFC,V6,14/33] qcow2: Create qcow2_is_cluster_to_dedup.

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Submitter Benoît Canet
Date Feb. 6, 2013, 12:31 p.m.
Message ID <1360153926-9492-15-git-send-email-benoit@irqsave.net>
Download mbox | patch
Permalink /patch/218640/
State New
Headers show

Comments

Benoît Canet - Feb. 6, 2013, 12:31 p.m.
Signed-off-by: Benoit Canet <benoit@irqsave.net>
---
 block/qcow2-cluster.c |   52 +++++++++++++++++++++++++++++++++++++++++++++++++
 block/qcow2.h         |    4 ++++
 2 files changed, 56 insertions(+)
Stefan Hajnoczi - Feb. 7, 2013, 9:53 a.m.
On Wed, Feb 06, 2013 at 01:31:47PM +0100, Benoît Canet wrote:
> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
> index 5b1d20d..fedcf57 100644
> --- a/block/qcow2-cluster.c
> +++ b/block/qcow2-cluster.c
> @@ -514,6 +514,58 @@ out:
>      return ret;
>  }
>  
> +/* Check if a cluster is to deduplicate given it's index

s/it's/its/

> + *
> + * @index:         The logical index of the cluster starting from 0
> + * @physical_sect: The physical sector of the cluster as return value
> + * @err:           0 on success, negative on error
> + * @ret:           True if the cluster is to deduplicate else false
> + */
> +bool qcow2_is_cluster_to_dedup(BlockDriverState *bs,
> +                               uint64_t index,
> +                               uint64_t *physical_sect,
> +                               int *err)
> +{
> +    BDRVQcowState *s = bs->opaque;
> +    unsigned int l1_index, l2_index;
> +    uint64_t offset;
> +    uint64_t l2_offset;
> +    uint64_t *l2_table = NULL;
> +
> +    *physical_sect = 0;
> +    *err = 0;
> +
> +    l1_index = index >> s->l2_bits;
> +
> +    if (l1_index >= s->l1_size) {
> +        return false;
> +    }
> +
> +    /* no l1 entry */
> +    if (!(s->l1_table[l1_index] & QCOW_OFLAG_COPIED)) {
> +        return false;
> +    }

Why check QCOW_OFLAG_COPIED?  Try this from qcow2_get_cluster_offset():

  l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
  if (!l2_offset) {
      ret = QCOW2_CLUSTER_UNALLOCATED;
      goto out;
  }

Patch

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 5b1d20d..fedcf57 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -514,6 +514,58 @@  out:
     return ret;
 }
 
+/* Check if a cluster is to deduplicate given it's index
+ *
+ * @index:         The logical index of the cluster starting from 0
+ * @physical_sect: The physical sector of the cluster as return value
+ * @err:           0 on success, negative on error
+ * @ret:           True if the cluster is to deduplicate else false
+ */
+bool qcow2_is_cluster_to_dedup(BlockDriverState *bs,
+                               uint64_t index,
+                               uint64_t *physical_sect,
+                               int *err)
+{
+    BDRVQcowState *s = bs->opaque;
+    unsigned int l1_index, l2_index;
+    uint64_t offset;
+    uint64_t l2_offset;
+    uint64_t *l2_table = NULL;
+
+    *physical_sect = 0;
+    *err = 0;
+
+    l1_index = index >> s->l2_bits;
+
+    if (l1_index >= s->l1_size) {
+        return false;
+    }
+
+    /* no l1 entry */
+    if (!(s->l1_table[l1_index] & QCOW_OFLAG_COPIED)) {
+        return false;
+    }
+
+    l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
+
+    *err = l2_load(bs, l2_offset, &l2_table);
+    if (*err < 0) {
+        return false;
+    }
+
+    l2_index = index & (s->l2_size - 1);
+
+    offset = be64_to_cpu(l2_table[l2_index]);
+    *physical_sect = (offset & L2E_OFFSET_MASK) >> 9;
+
+    *err = qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
+    if (*err < 0) {
+        return false;
+    }
+
+    return offset & QCOW_OFLAG_TO_DEDUP;
+}
+
 /*
  * get_cluster_table
  *
diff --git a/block/qcow2.h b/block/qcow2.h
index 1ee4c13..becb2f8 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -437,6 +437,10 @@  int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m);
 int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
     int nb_sectors);
 int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors);
+bool qcow2_is_cluster_to_dedup(BlockDriverState *bs,
+                               uint64_t index,
+                               uint64_t *physical_sect,
+                               int *ret);
 
 /* qcow2-snapshot.c functions */
 int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info);